Electronic fuze

ABSTRACT

A fuze for ordnance projectiles to be launched from a vehicle is armed, after separation from its launcher, by mechanical closure of switches with the aid of a delayed-action squib detonating by an electric charge stored on a capacitor. The fuze system includes means for charging the above capacitor at the time of launch, thus insuring the inert state of the fuze under conditions of storage, transportation and loading into the launch vehicle.

United States Patent 1 [111 3,739,726 Pintell June 19, 1973 ELECTRONIC FUZE 2,735,993 2/1956 Humphrey 333 91 5 1 R t n. t l [7 Inventor ober Pm New N Y Primary Examiner-Benjamin A. Borchelt [73] Assignee: Intron International, Inc., Congers, Assistant Examiner-Thomas H. Webb N.Y. AttorneyKarl F. Ross [22] Filed: Aug. 17, 1970 57 ABSTRACT [21] Appl' 64297 A fuze for ordnance projectiles to be launched from a 4 vehicle is armed, after separation from its launcher, by

[52] US. Cl..... 102/70.2 R mechanical closure of switches with the aid of a [51] Int. Cl. F42c' 11/04, F42c 11/06, F42c 15/40 delayed-action squib detonating by an electric charge [58] Field of Search 102/702 R, 702 P, stored on a capacitor. The fuze system includes means 102/702 A for charging the above capacitor at the time of launch, thus insuring the inert'state of the fuze under condi- [56] References Cited tions of storage, transportation and loading into the UNITED STATES PATENTS launch vehlcle- 3,560.86?) 2/1971 Baumoel 102/702 10 Claims, 9 Drawing Figures PROJECT/l. E

REASE DETONATOR Patented June 19, 1973 3,739,726

4 Sheets-Sheet 1 PYLON LAUNCH VEHICLE PROJHT'ILE DEI'ONATOR er ream'mrrsz I01 RECEIVE-F 305' L 301 K l .900 P FIG. 4

Attorney Patented June 19, 1973 I 4 Sheets-Sheet 2 Patented June 19, 1973 3,739,726

4 Sheets-Sheet 3 FIG. 6

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Robert H. Pintel! INVENTOR.

BY O -j Attorney Patented June 19, 1973 3,739,726

4 Sheets-Sheet 4.

new 061: JasQ ip L 369 Q Roberf H. Pinfell I N VEN TOR.

G A Rois Attorney ELECTRONIC FUZE My present invention relates to a firing system for an explosive charge, hereinafter referred to as a fuze.

In the field of ordnance technology the function of a fuze is to ensure the safety of the weapon and its crew up to and during the launching of the projectile with its warhead. As a rule, therefore, the fuze is provided with means for inhibiting the detonation of the explosive charge in the vehicle or weapon in which it is carried, and for some time after it is launched from its carrier on its flight toward the target.

One of the prime characteristics of the ideal fuze is, consequently, its inertness under conditions of storage, transportation and preparation for launching or firing. Many of the conventional fuze designs are deficient in this respect. Powered by electrical or mechanical means for storing the energy required for their functioning, they are susceptible to actuation by external influences such as shock, vibration, stray electrical or magnetic fields and, ultimately, deliberate action of an enemy, e.g. in the form of electronic countermeasures. As a consequence of this unreliability factor, fuzes are frequently handled apart from the warheads they are meant to actuate and are only brought into the projectile assembly at the last possible moment, e.g. by insertion into an artillery shell just prior to its loading into the gunbarrel.

It is, therefore, the general object of my present invention to provide an improved fuze system which is safe from premature activation and foolproof in operation.

A related object is to provide a system of this character allowing a projectile so equipped to carry its warhead during transportation and handling without risk of accident.

In accordance with this invention I provide, in a fuze comprising an activating circuit for a detonator aboard a projectile to be launched from a carrier, one or more condensers serving as capacitive storage means for detonating energy, no other supply of such energy being present on the projectile. At the time of launch, i.e.

upon incipient separation of the projectile from its carrier, the storage capacitor or capacitors are charged by the transfer of electrical energy from a current source on the carrier. v

Advantageously, pursuant to another feature of my invention, the activating circuit includes a pyrotechnic switch in which an ancillary charge, only sufficient to close an initially open mechanical circuit breaker, is set off with a certain delay upon the charging of the storage capacitor. Even if, accidentally, this ancillary charge should be detonated prematurely, the main detonator associated with the warhead will not go into action unless the capacitor is fully charged and other conditions are fulfilled, e. g. the verification of certain operating parameters by a computer aboard the projectile. As a particular safety measure, a protective switch closed only upon the tensioning of a rupturable lanyard may prevent untimely discharge of a firing condenser through the detonator of the warhead.

In accordance with a more specific feature of my invention, the storage capacitor can be charged at the time of launch by a switch or set of switches in series with a conductor forming part of an umbilical cord initially extending from the mother vehicle or carrier to the projectile. Alternatively, or in addition, this capacitor could be charged by magnetic induction or by radio-frequency wave transmission, the energy-transfer means in this case including a transmitter aboard the carrier and a corresponding receiver aboard the projectile. In any event, the capacitive storage of sufficient energy to activate the firing circuit is made possible through the use of solid-state electronic components in the fuze whose inherent low power consumption limits the dissipation of the stored energy.

Thus, the fuze embodying my invention is completely inert prior to activation and, aside from being safe to handle, has an unlimited shelf life.

The above and other features of my invention will now be described in detail with reference to the accompanying drawing in which:

FIG. 1 is a diagrammatic illustration of a launch vehicle with a suspended projectile incorporating a fuze according to the invention;

FIG. 2 is a diagram of the major components of the fuze system shown in FIG. 1;

I FIG. 3 is a block diagram of the logic elements incorporated in the system of FIG. 2;

FIG. 4 is a diagram of an embodiment of a charging circuit for storage capacitor included in that system;

FIG. 5A is a diagrammatic view of a switching mechanism for the charging circuit of FIG. 4;

FIGS. 53 and 5C are sectional detail views relating to the mechanism of FIG. 5A; and

FIGS. 6 and 7 illustrate projective circuits for the fuze detonator.

In FIG. 1 I have shown a launch vehicle V with an integral release pylon carrying a projectile P. A slack umbilical cord 200 extends from pylon 200 to the projectile which includes an initially deactivated fuze 300, a detonator 400 controlled by the fuze, and a warhead 500 destined to be set off by the detonator. Pylon 100 contains a command circuit communicating with a logic network in fuze 300 via a transmitting aerial 101 and a receiving aerial 301 as well as by way of electrical circuits included in umbilical cord 200.

FIG. 2 shows details of components 100, 200, 300, 400 and 500 referred to above. The command circuit of pylon 100 includes a power supply 102 feeding a controller 103 which, in response to a signal generated or received aboard the vehicle, actuates a conventional release mechanism 104 to launch the projectile P. Controller 103 also energizes a transmitter 105 equipped with antenna 101. A power cable 106 extends from transmitter 105 within umbilical cord 200 to a bus bar 306 within fuze 300, this bus bar being initially separated from cable 106 by a switching mechanism generally designated 210; and advantageous construction of this mechanism will be described in greater detail hereinafter with reference to FIGS. 5A, 5B, 5C.

Bus bar 306 forms part of a charging circuit for an initially discharged storage condenser 307 and also extends to other circuit components aboard the projectile P, including a set of sensors 308 and a logic network 310 hereinafter referred to as a first computer. Command signals from transmitter 105 reach the computer 310, as well as a similar network 320 hereinafter designated a second computer, via one or more leads 109 tied by a connection 209 within umbilical cord 200 to a similar lead or set of leads 309 in fuze 300. Sensors 308, which may be responsive to such external parameters as altitude, ground speed and the like, also deliver signals to the first and second computers 310, 320 by way of conductors 331 and 332, respectively.

An output lead 333 of computer 310 extends to a pyrotechnic switch 340 which, when set off, energizes a lead 334 to supply power to the second computer 320. The latter, in response to information from sensors 308 and possibly to signals transmitted from mother vehicle V by way of antennas 101, 301 and a receiver 305 connected to the latter antenna, then sends a trigger pulse over a lead 335 to detonator 400 which thereupon fires a charge 501 in warhead 500.

FIG. 3 shows details of computers 310, 320 and pyrotechnic switch 340. A rupturable lanyard 350, tied to mother vehicle V, terminates at an initially open safety switch 351 to close it upon being tightened just prior to rupture as the two vehicles separate; lanyard 350 may be independent of umbilical cord 200 or form part thereof. Switch 351 thereupon connects the main bus bar 306 to an ancillary bus bar 352 from which branches extend to two AND gates 311 and 312 in computer 310 and an AND gate 321 in computer 320. AND gate 311 also has an input connected directly to bus bar 306, by way of an extension 316 thereof, and works through a delay network 313 into a comparator 314 which also receives a reference voltage, derived from lead 316, through a unit 317, e.g. a potentiometer. The output lead 318 of comparator 314 terminates at AND gate 312 which energizes an input of a further AND gate 319, another input of the latter AND gate being tied to the output lead 332 of sensing circuit 308. AND gate 319, like AND gate 321 in computer 320, is representative of a more elaborate logic matrix designed to evaluate the various signals from sensing circuit 308.

When AND gate 319 responds, i.e. upon receipt of the proper combination of signals from sensors 308 in the conductive state of AND gate 312, it unblocks a normally blocked gate 341 in the power circuit leading from bus bar 306 to a squib 342 forming part of the pyrotechnic switch 340. This pyrotechnic switch further includes a mechanical circuit breaker 343 which, via a piston 344 displaced by the detonation of squib 342, is closed to supply power to computer 320 which includes another normally blocked gate 322. AND gate 321, which may already be conductive at that instant, opens the gate 322 to complete a charging circuit from bus bar 306 to a firing condenser 323 whose capacitance is considerably less than that of storage condenser 307. Thus, the residual charge of condenser 307 (after energization of the various circuits fed from bus bar 306) suffices to raise the potential of condenser 323 to the level required for activating the detonator 400 by way of output lead 335.

The initial charging of storage capacitor 307 may be accomplished in various ways. As illustrated at FIG. 4, high-frequency energy communicated from transmitter 105 to receiver 305 with the aid of antennas 101 and 301 can be rectified, in a circuit symbolized by a diode 353, to apply a d-c voltage to bus bar 306 for the time necessary to accumulate a suitable charge.

Capacitor 307 may be precharged, to a level insufficient to set off the squib 342, via lead 106 and switch 210 (FIG. 2) which for this purpose may be closed for a limited period just prior to the severing of umbilical cord 200; the transmission of r-f energy via aerials 101 and 301 is then required only to supplement the preliminary charge of the capacitor. Thus, an electronic breakdown device in series with delay network 313 (FIG. 3), such as a Zener diode 354, may serve to prevent operation of comparator 314 even upon closure of safety switch 351 if the condenser voltage has not been brought up to the specified level.

It is, however, also possible to rely exclusively upon the umbilical cord 200 for the charging of condenser 307 at the instant of separation. This has been illustrated in FIGS. 5A 5C where the pylon is shown provided with a switch box 1 10 connected via the cable 106 with a similar switch box 360 on projectile P. Wire 106 has two sections 106a, 106k interconnected by a loop 1060 which is spanned by a spring 21 1. Switch box 110, illustrated in detail in FIG. 5B, contains an armature 111 biased by a spring 112 away from a confronting contact 113 which is connected to the end of a lead 114 emanating from power supply 102 and traversing the controller 103 of FIG. 2. Switch box 360 (FIG. 5C), similarly, has an armature 361 biased by a spring 362 away from a contact 363 connected to bus conductor 306. Box 360 also comprises a jack 364 in which the output end of cable portion 106b is frictionally held by a mating plug 365.

With cable portion 106a directly connected to armature 111 and jack 364 tied to armature 361 by a wire link 366, the incipient separation of projectile P from its mother vehicle V reduces the slack of umbilical cord 200 so that cable 106 begins to stretch against the tensile force of spring 211. Since springs 112 and 362 are weaker than spring 211, contacts 111, 113 and 361, 363 close substantially simultaneously at this point to let the full output of power supply 102 (stepped down, if necessary, in controller 103) charge the capacitor 307 over a low-resistance path whereby the condenser potential is brought to the desired level during the brief period available for this operation. As soon as the tension of spring 211 has reached a critical limit, plug 365 is withdrawn from jack 364 while conductive link 209 (FIG. 2), representative of any number of leads not shown in FIGS. 5A 5C, is similarly severed. With bus bar 306 insulated from ground, the charge on condenser 307 remains trapped until released in the manner described above.

FIG. 6 illustrates an additional safety measure that may be used to prevent untimely activation of detonator 400. Firing condenser 323 is here shown shunted by a clamp circuit including a field-effect transistor 355 whose gate, connected to lead 352, is energized only upon the closure of circuit breaker 351 by lanyard 350 (FIG. 3). A resistor 356 in the output lead 335 insulates the detonator against stray pulses.

FIG. 7 shows an alternate protective circuit including a controlled rectifier 357 whose gate-cathode circuit includes a resistor 358 bridged by the field-effect transistor 355. In this instance, the gate of controlled rectifier 357 is connected to lead '352 whereas the gate of transistor 355 is energizable by a proximity sensor 357. Resistor 356 is here connected in series with controlled rectifier 357 and firing condenser 323. Thus, energization of lead 335 is blocked even in the presence of voltage on lead 352 so that condenser 323 cannot discharge into the detonator 400 (FIGS. 2 and 3) as long as FET 355 is passive; only upon detection of the proximity of the target, by means of sensor 359, can the warhead be exploded.

I claim:

1. A firing system for an explosive charge aboard a projectile to be launched from a carrier, comprising:

a detonator for said charge aboard said projectile;

an activating circuit for said detonator on said projectile, said circuit including capacitive storage means as its sole supply of activating energy;

a source of charging current for said storage means on said carrier;

transfer means operative only upon incipient separation of said projectile from said carrier for instantly charging said storage means with current from said source; and

sensing means independent of said transfer means on said projectile for completing a firing circuit to said detonator from said storage means, subsequently to the charging thereof, in response to external parameters.

2. A system as defined in claim 1 wherein said transfer means includes high-frequency radio transmission means on said carrier and corresponding receiving means on said projectile.

3. A system as defined in claim 1 wherein said transfer means includes a conductor extending slack from said carrier to said projectile and normally open switch means in series with said conductor momentarily closable upon a tensioning of the latter.

4. A system as defined in claim 3 wherein said switch means comprises a pair of switches at opposite ends of said conductor.

5. A system as defined in claim 1 wherein said activating circuit includes a normally open mechanical circuit breaker between said storage means and said detonator, and pyrotechnic switch means triggerable by said storage means upon a charging thereof for closing said circuit breaker.

6. A system as defined in claim 5 wherein said activating circuit further includes delay means inserted be tween said storage means and said pyrotechnic switch means for retarding the closure of said circuit breaker.

7. A system as defined in claim 1 wherein said activating circuit includes a firing condenser of a capacitance substantially less than that of said storage means, said condenser having a discharge path through said detonator.

8. A system as defined in claim 7 wherein said firing condenser is provided with protective circuitry including an initially open safety switch closable upon separation of said projectile from said carrier for blocking premature discharge of said condenser through said detonator.

9. A system as defined in claim 8 wherein said protective circuitry includes a clamping network in shunt with said condenser.

10. A system as defined in claim 8 wherein said safety switch is provided with a rupturable lanyard tied to said carrier for closing said safety switch upon incipient separation. 

1. A firing system for an explosive charge aboard a projectile to be launched from a carrier, comprising: a detonator for said charge aboard said projectile; an activating circuit for said detonator on said projectile, said circuit including capacitive storage means as its sole supply of activating energy; a source of charging current for said storage means on said carrier; transfer means operative only upon incipient separation of said projectile from said carrier for instantly charging said storage means with current from said source; and sensing means independent of said transfer means on said projectile for completing a firing circuit to said detonator from said storage means, subsequently to the charging thereof, in response to external parameters.
 2. A system as defined in claim 1 wherein said transfer means includes high-frequency radio transmission means on said carrier and corresponding receiving means on said projectile.
 3. A system as defined in claim 1 wherein said transfer means includes a conductor extending slack from said carrier to said projectile and normally open switch means in series with said conductor momentarily closable upon a tensioning of the latter.
 4. A system as defined in claim 3 wherein said switch means comprises a pair of switches at opposite ends of said conductor.
 5. A system as defined in claim 1 wherein said activating circuit includes a normally open mechanical circuit breaker between said storage means and said detonator, and pyrotechnic switch means triggerable by said storage means upon a charging thereof for closing said circuit breaker.
 6. A system as defined in claim 5 wherein said activating circuit further includes delay means inserted between said storage means and said pyrotechnic switch means for retarding the closure of said circuit breaker.
 7. A system as defined in claim 1 wherein said activating circuit includes a firing condenser of a capacitance substantially less than that of said storage means, said condenser having a discharge path through said detonator.
 8. A system as defined in claim 7 wherein said firing condenser is provided with protective circuitry including an initially open safety switch closable upon separation of said projectile from said carrier for blocking premature discharge of said condenser through said detonator.
 9. A system as defined in claim 8 wherein said protective circuitry includes a clamping network in shunt with said condenser.
 10. A system as defined in claim 8 wherein said safety switch is provided with a rupturable lanyard tied to said carrier for closing said safety switch upon incipient separation. 